Mechanical performance of modular FRP-steel composite beams for building construction

Abstract

This paper presents an experimental and modelling investigation into modular web-flange fibre-reinforced polymer (FRP)-steel composite systems for use in building floor construction. The modular FRP slabs are formed from adhesively bonding pultruded box profiles sandwiched between two flat panels. They are then connected via adhesive or novel bolted connections to steel beams to form a composite system. Two different fibre (pultrusion) configurations are investigated in this paper: flat panel pultrusion with direction either parallel or perpendicular to the box profiles. Composite beams were tested under four-point bending and evaluated for bending stiffness, load-carrying capacity, and the degree of composite action within the FRP web-flange sandwich slab and that provided by the shear connections. All the composite beams showed ductile load–deflection responses, with yielding of the composite beam commencing prior to failure of the FRP slabs. Furthermore, adhesive bonding provided full composite action, but the novel bolted connections with a certain spacing provided either full or partial composite action, dependent on the pultrusion configuration of the FRP slab. Finally, an analytical procedure is presented to evaluate the bending stiffness and load-carrying capacity of the composite beams. Finite element analysis was also employed in this study, showing good comparisons to the experimental results.